New piezoelectric transducers for therapeutic ultrasound.

Therapeutic ultrasound (US) has been of increasing interest during the past few years. However, the development of this technique depends on the availability of high-performance transducers. These transducers have to be optimised for focusing and steering high-power ultrasonic energy within the target volume. Recently developed high-power 1-3 piezocomposite materials bring to therapeutic US the exceptional electroacoustical properties of piezocomposite technology: these are high efficiency, large bandwidth, predictable beam pattern, more flexibility in terms of shaping and definition of sampling in annular arrays, linear arrays or matrix arrays. The construction and evaluation of several prototypes illustrates the benefit of this new approach that opens the way to further progress in therapeutic US.

[The effects of heparin in underdevelopment of the fetus due to maternal vascular conditions (author's transl)]. / Effets de l'héparine dans l'hypotrophie foetale d'origine vasculaire maternelle.

The use of heparin to interfere with the appearance of fetal maldevelopment (or to correct it) is logical but the results are difficult to prove because it is difficult to be certain of early diagnosis at the time when therapy has the best chances of being efficacious. The authors compare two groups of pregnant women in whom the muscular vascular tone of the cervix is abolished. The second group was treated with heparin. The results are statistically significant and prove that treatment with heparin is well based in cases of underdevelopment of the fetus when it is due to abnormalities in the maternal microscopic circulation (acute atherosis). They confirm that the enzyme, hormone and ultrasound parameters return to normal from the beginning of treatment with heparin.

[Dynamic study of tissue circulation in the cervix uteri and the prognosis of the newborn infant]. / Etude dynamique de la circulation tissulaire dans le col utérin et pronostic néonatal.

A new machine has been developed to measure heat dissipated in the tissues especially by convection linked to the blood flow. Its use is simple and without any danger as far as application to the pregnant cervix goes. New discoveries are presented. A new concept of the micro-circulation is considered together with the consequences. The practitioner may be able to draw conclusions as to the prognosis, as to whether a small-for-dates fetus together with or without premature labour is likely. This depends on the tracings obtained which register the intrinsic activity of the periarteriolar muscles.